The social networks of colonies of social insects have been extensively studied as model biological networks.
Ant social networks have three main types of individuals or castes. [1] The three types - the queen, workers, and drones - all serve a specific purpose within the colony. [1] The queen is the reproductive member of the colony. Some ant species will only have one queen, while others will form polygynous colonies of multiple queens, such as Argentine ants Linepithema humile. [2] The workers are responsible for supporting the queen, maintenance, and foraging. Unlike queens and drones, workers are born wingless. Some polymorphic ants can have workers who look morphologically very different from each other, with specific jobs and behaviours. [1] [3] Examples of these polymorphisms can be seen in the big-headed ants Pheidole dentata, where the different castes of workers (majors with large heads and minors with regular sized heads) increase colony efficiency and what the colony is able to accomplish. [4] The drones are the only males in ant social structures, and have little to do with colony activities. [5] Their sole purpose is to transport DNA. [5] The drones leave the colony on a nuptial flight or mating flight, find a virgin queen to reproduce with, and then die shortly after. [5]
Bee and wasp social structure is very similar to that of ants, except all of the members have wings. Both bees and ants communicate effectively using pheromone methods. For example, honey bees use brooding pheromone to increase eggs laid by the queen. [6] Unlike ants, bees also use "dance language". This very complex behaviour allows foraging bees to communicate to their sisters the location of resources and dangers in the foraging space all through dancing movements. [7] However, inside the dark chambers of the nest itself, complex pheromone systems are used to communicate and organize the group. [6]
Termites, in the order Blattodea, also have an advanced social network. The termite social network evolved separately from the Hymenoptera, and has some key differences. Instead of just a reproductive queen, termites have a reproductive royal pair, the king and queen, that stay in the colony to produce offspring. [8] The other colony members are divided into workers and soldiers. [8] Workers and soldiers can be male or female, and lack wings, eyes, and developed sex organs, unlike the reproductive members. [9] Workers perform all of the colony's maintenance, such as caring for young, cleaning, building tunnels, and feeding the other members. [9] The primary goal of the soldiers is to defend and guard the entrance to the colony. [10]
The network of trophallaxis events differs from the network of social contacts. In the trophallaxis network of Lasius niger, foragers have higher betweenness and centrality than domestic workers. The domestic workers appear to form three clusters. [11] There also appear to be some domestic workers which act as intermediaries between foragers and other domestic workers. [11]
In some species, during nest emigration, there is a minority of workers who actively search for new nest sites. When they find a promising site they recruit nest-mates to show them the site. The nest-mates can in turn recruit more workers and when a critical mass of ants moves back and forth between the old site and a particular new site then the whole colony moves. Recruitment generally occurs via tandem running, and the emigration process can be modelled as a directed network where edges connect workers who performed a tandem run together, and the directionality shows which worker led and which worker followed. The density and complexity of these networks appear to increase with indecision, [12] and the core of the networks consists predominantly of the subcaste of workers specialised in finding new sites and recruiting other workers. [12]
Living in large colonies in confined spaces creates a risk of pathogen spreading. Insects in social networks show many anti-pathogen behaviours to prevent the spread of infection. An example of this behaviour is the pathogen alarm behaviour in termites. [13] If a termite detects itself being infected with pathogen spores, it will produce a vibratory signal to warn the other colony members to stay away from it to prevent the spread of the fungi. [13]
Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22,000 species have been classified. They are easily identified by their geniculate (elbowed) antennae and the distinctive node-like structure that forms their slender waists.
Termites are a group of detritophagous eusocial insects which consume a wide variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bodied and often unpigmented worker caste for which they have been commonly termed "white ants"; however, they are not ants, to which they are only distantly related. About 2,972 extant species are currently described, 2,105 of which are members of the family Termitidae.
In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey.
Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) or anus-to-mouth (proctodeal) feeding. Along with nutrients, trophallaxis can involve the transfer of molecules such as pheromones, organisms such as symbionts, and information to serve as a form of communication. Trophallaxis is used by some birds, gray wolves, vampire bats, and is most highly developed in eusocial insects such as ants, wasps, bees, and termites.
The pharaoh ant is a small (2 mm) yellow or light brown, almost transparent ant notorious for being a major indoor nuisance pest, especially in hospitals. A cryptogenic species, it has now been introduced to virtually every area of the world, including Europe, the Americas, Australasia and Southeast Asia. It is a major pest in the United States, Australia, and Europe. The ant's common name is possibly derived from the mistaken belief that it was one of the Egyptian (pharaonic) plagues.
Blattodea is an order of insects that contains cockroaches and termites. Formerly, termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests they evolved from within the cockroach lineage, cladistically making them cockroaches as well. The Blattodea and the mantis are now all considered part of the superorder Dictyoptera. Blattodea includes approximately 4,400 species of cockroach in almost 500 genera, and about 3,000 species of termite in around 300 genera.
Bombus terrestris, the buff-tailed bumblebee or large earth bumblebee, is one of the most numerous bumblebee species in Europe. It is one of the main species used in greenhouse pollination, and so can be found in many countries and areas where it is not native, such as Tasmania. Moreover, it is a eusocial insect with an overlap of generations, a division of labour, and cooperative brood care. The queen is monogamous which means she mates with only one male. B. terrestris workers learn flower colours and forage efficiently.
Bombus ternarius, commonly known as the orange-belted bumblebee or tricolored bumblebee, is a yellow, orange and black bumblebee. It is a ground-nesting social insect whose colony cycle lasts only one season, common throughout the northeastern United States and much of Canada. The orange-belted bumblebee forages on Rubus, goldenrods, Vaccinium, and milkweeds found throughout the colony's range. Like many other members of the genus, Bombus ternarius exhibits complex social structure with a reproductive queen caste and a multitude of sister workers with labor such as foraging, nursing, and nest maintenance divided among the subordinates.
Task allocation and partitioning is the way that tasks are chosen, assigned, subdivided, and coordinated within a colony of social insects. Task allocation and partitioning gives rise to the division of labor often observed in social insect colonies, whereby individuals specialize on different tasks within the colony. Communication is closely related to the ability to allocate tasks among individuals within a group. This entry focuses exclusively on social insects. For information on human task allocation and partitioning, see division of labour, task analysis, and workflow.
Eusociality is the highest level of organization of sociality. It is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform behaviors characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.
The green-head ant is a species of ant that is endemic to Australia. It was described by British entomologist Frederick Smith in 1858 as a member of the genus Rhytidoponera in the subfamily Ectatomminae. These ants measure between 5 and 7 mm. The queens and workers look similar, differing only in size, with the males being the smallest. They are well known for their distinctive metallic appearance, which varies from green to purple or even reddish-violet. Among the most widespread of all insects in Australia, green-head ants are found in almost every Australian state, but are absent in Tasmania. They have also been introduced in New Zealand, where several populations have been established.
Zootermopsis angusticollis is a species of termite (Isoptera) in the family Archotermopsidae, a group known as the Pacific dampwood termites, or the rottenwood termites. As their name suggests, the dampwood termites can only survive by living off of wood that contains high amounts of moisture. They are found along the wet environments of the Pacific coast of North America. Most are found in the states of California, Oregon, Washington, Idaho, Western Nevada and in southern British Columbia. Termites are well known to be destroyers of wood, and although the dampwood termites can cause some damage, they are not as notoriously known to cause as much damage to buildings as the drywood termites. They occasionally have been carried to other parts of the country through wood shipments, but have not been able to become established in these areas due to undesirable environmental conditions.
Bumblebees, like the honeybee collect nectar and pollen from flowers and store them for food. Many individuals must be recruited to forage for food to provide for the hive. Some bee species have highly developed ways of communicating with each other about the location and quality of food resources ranging from physical to chemical displays.
Trail pheromones are semiochemicals secreted from the body of an individual to affect the behavior of another individual receiving it. Trail pheromones often serve as a multi purpose chemical secretion that leads members of its own species towards a food source, while representing a territorial mark in the form of an allomone to organisms outside of their species. Specifically, trail pheromones are often incorporated with secretions of more than one exocrine gland to produce a higher degree of specificity. Considered one of the primary chemical signaling methods in which many social insects depend on, trail pheromone deposition can be considered one of the main facets to explain the success of social insect communication today. Many species of ants, including those in the genus Crematogaster use trail pheromones.
Worker policing is a behavior seen in colonies of social hymenopterans whereby worker females eat or remove eggs that have been laid by other workers rather than those laid by a queen. Worker policing ensures that the offspring of the queen will predominate in the group. In certain species of bees, ants and wasps, workers or the queen may also act aggressively towards fertile workers. Worker policing has been suggested as a form of coercion to promote the evolution of altruistic behavior in eusocial insect societies.
Megaponera analis is the sole species of the genus Megaponera. They are a strictly termite-eating (termitophagous) ponerine ant species widely distributed in Sub-Saharan Africa and most commonly known for their column-like raiding formation when attacking termite feeding sites. Their sophisticated raiding behaviour gave them the common name Matabele ant after the Matabele tribe, fierce warriors who overwhelmed various other tribes during the 1800s. With some individuals reaching up to 25 millimetres (0.98 in) in length, M. analis is one of the world's largest ants.
This is a glossary of terms used in the descriptions of ants.
Pleometrosis is a behavior observed in social insects where colony formation is initiated by multiple queens primarily by the same species of insect. This type of behavior has been mainly studied in ants but also occurs in wasps, bees, and termites. This behavior is of significant interest to scientists particularly in ants and termites because nest formation often happens between queens that are unrelated, ruling out the argument of inclusive fitness as the driving force of pleometrosis. Whereas in other species such as wasps and bees co-founding queens are often related. The majority of species that engage in pleometrosis after the initial stages of colony formation will reduce their colonies number of queens down to one dominant queen and either kill or push out the supernumerary queens. However there are some cases where pleometrosis-formed colonies keep multiple queens for longer than the early stages of colony growth. Multiple queens can help to speed a colony through the early stages of colony growth by producing a larger worker ant population faster which helps to out-compete other colonies in colony-dense areas. However forming colonies with multiple queens can also cause intra-colony competition between the queens possibly lowering the likelihood of survival of a queen in a pleometrotic colony.
Scaptotrigona postica is a species of stingless bee that lives mainly in Brazil. It is a eusocial bee in the tribe Meliponini. S. postica is one of 25 species in the genus Scaptotrigona and is a critical pollinator of the tropical rain forests of Brazil. They construct their nests in hollowed sections of tree trunks, allowing for effective guarding at the nest entrance. This species shows colony structure similar to most members of the Meliponini tribe with three roles within the colony: queen, worker, and male. S. postica individuals have different forms of communication from cuticular hydrocarbons to pheromones and scent trails. Communication is especially useful during worker foraging for nectar and pollen through the Brazilian tropical rain forests. S. postica is a very important pollinator of the Brazilian tropical rain forests and is widely appreciated for its honey. Stingless bees account for approximately 30% of all pollination of the Brazilian Caatinga and Pantanal ecosystems and up to 90% of the pollination for many species of the Brazilian Atlantic Forest and the Amazon.
Social immunity is any antiparasite defence mounted for the benefit of individuals other than the actor. For parasites, the frequent contact, high population density and low genetic variability makes social groups of organisms a promising target for infection: this has driven the evolution of collective and cooperative anti-parasite mechanisms that both prevent the establishment of and reduce the damage of diseases among group members. Social immune mechanisms range from the prophylactic, such as burying beetles smearing their carcasses with antimicrobials or termites fumigating their nests with naphthalene, to the active defenses seen in the imprisoning of parasitic beetles by honeybees or by the miniature 'hitchhiking' leafcutter ants which travel on larger worker's leaves to fight off parasitoid flies. Whilst many specific social immune mechanisms had been studied in relative isolation, it was not until Sylvia Cremer et al.'s 2007 paper "Social Immunity" that the topic was seriously considered. Empirical and theoretical work in social immunity continues to reveal not only new mechanisms of protection but also implications for understanding of the evolution of group living and polyandry.